Light-responsive voltage regulator for alternating-current source

ABSTRACT

A voltage regulator wherein a pair of input circuit lines are provided and one of the circuit lines has connected in series therewith a bidirectional current control device having a control electrode for receiving control signals in response to the output voltage of a circuit portion of the voltage regulator. The control signals applied to the control electrode of the current control device are developed in response to light intensity of a light-emitting element connected to and energized by, the circuit portion.

I United States Patent [11135991182 [72] In n EmllE- Basie! 3,335,318 8/1967 Yancey 323/21 UX Chicago, lll- 3,344,311 9/1967 Nuckolls 323/22 sc 211 pp 5,050 3,361,931 1/1968 Vollrath 323/21 ux Filed Jan. 22, 1970 3,414,798 12/1968 Nielsen..... 323/21 X 1 Patented Aug-10,1971 3,450,939 6/1969 Misencik.. 323/36 ux 1 Assignee Motorolmlm- 3,463,990 8/1969 Ross 323/21 ux Franklin Pa k, 3,475,677 10/1969 Swinehart et a1. 323/21 Primary Examiner-J. D. Miller 1541 LIGHT-RESPONSIVE VOLTAGE REGULATOR Aviva"! Examiner-A Pellinen FOR ALTERNATlNG-CURRENT SOURCE o- Mueller and Aichele 6 Claims, 2 Drawing Figs.

U.S. A voltage regulator wherein a pair of inpur ir:

' 323/22 sC1323/241323/361323/39 cuit lines are provided and one of the circuit lines has con- [Sl] ll. 6051/44 e t d in eries therewith a bidirectional current Control 1 Field of sarch 32301122 device having a control electrode for receiving control signals v 39 in response to the output voltage of a circuit portion of the volta e regulator. The control signals a lied to the control [56] References cued electfode of the current control devige are developed in UNITED STATES PATENTS response to light intensity of a light-emitting element con- 3,252,0l0 5/1966 Buttenhofi' 323/24 UX nected to and energized by, the circuit portion.

,FILTER CIRCUIT TO RECTIFIER AND BACKGROUND OF THE INVENTION This invention relates generally to alternating-current voltage-regulators, and more particularly to such voltage regulators which control current flow of both half-cycles of an applied alternating-current voltage. I

The use of alternating-current voltage regulators is a well known and often used expedient to compensate for undesired voltage variations which may occur within a standard wall receptacle outlet. Although power companies which generate electricity for commercial use try to maintain the voltage am plitude of the electrical power delivered to their users within a minimum voltage variation, it becomes a very difficult task to maintain such voltage regulation because of unknown high current drains which may, and usually do, occur at random intervals within a given period of time. Therefore, when users of commercially available alternating-current voltage desire to operate certain kinds of electrical equipment which require a substantially constant voltage applied thereto, it becomes necessary for such users to incorporate voltage regulation means at the inputof such equipment.

Heretofore, many different kinds and variations of alternating-current voltage regulators have been incorporated at the input of various types of electrical equipment. However, many of the prior art voltage regulator systems tend to be inefficient in operation and expensive. The cost of such voltage regulators is of considerable importance when used in high volume production consumer products such as television and radio circuits because the added cost of voltage regulation forms part of the total cost of such products.

SUMMARY OF THE INVENTION Accordingly, it is an object of this invention to provide an alternating-current voltage regulator which regulates the volt age applied to a load circuit to a predetermined voltage value without being affected by a relatively wide range of voltage variations at the input lines of the regulator.

example, for connection to a conventional wall receptacle.

outlet. In the case where a step-up transformer is used, the primary winding thereof is connected in series with a bidirectional current control device having load electrodes in series with the primary winding and a control electrode for receiving control signals in response to the voltage output of a selected circuit portion at the secondary winding, or windings, of the transformer. Most advantageously, a light-responsive resistance element is connected in circuit with the control electrode of the current control device and in combination with a capacitance resistance network controlling the phase angle at which the current control device is rendered conductive to control the current flow through the primary winding of the transformer. The light-responsive resistance element is positioned adjacent a light-emitting element of any suitable configuration such as a conventional light bulb, the intensity of which varies in response to the voltage output of the selected circuit portion at the secondary winding of the transformer. Preferably, the light-responsive resistance element and the light-emitting element are positioned within a single casing so as to exclude any extraneous light from affecting the light-responsive resistance element. Preferably, voltage control means is connected in circuit with the light-emittingelement to provide manual selection of the light output thereof which, in turn, will set the desired voltage output 'of the voltage regulator within a given range of voltages.

Because of the effectiveness and low cost of the voltage regulator of this invention it has particular utility for use in television circuits, and particularly color television circuits. In

this arrangement, a high-frequency filter choke may be incor-.

porated in the input line to the voltage regulator in the conventional manner without affecting the operation of the voltage regulator. Also, a tap on one of the secondary windings of the transformer used in the voltage regulator may also be used for automatic degaussing of the color television picture tube in any well-known and conventional manner.

BRIEF DESCRIPTION OF THE DRAWINGS cuit.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1 there is seen an alternating-current voltage regulator'constructed in accordance with this invention and designated generally by reference numeral 10. A pair of input lines 12 and 14 are arranged for connection to any suitable source of alternating-current voltage, such as a conventional outlet receptacle. A first power receiving portion indicated by reference numeral 16 is provided for delivering a regulated voltage to any suitable load or electric current utilization means which mayinclude one or more rectifiers and a filter circuit. In the case where the voltage at the circuit portion 16 is ,to be substantially increased or decreased from that of the applied alternating-current voltage at circuit lines 12 and 14, a transformer 18 is provided which has a primary winding 18a thereof connected in series with a bidirectional multilayer current control device 20. Theload electrodes of the current control device 20 are connected directly in series O'with the primary winding 18a and a control electrode 20a thereof is connected to a resistance capacitance network 22 through a bidirectional threshold-switching device 24. The threshold voltage value of the bidirectional threshold-voltageswitching device 24 determines the minimum voltage required to fire the current control device 20 to cause current flow through the primary winding 18a.

In the illustrated embodiment resistance capacitance neti work 22 includes a pair of capacitors 26 and 28 having one end of each connected together by a pair of resistors 30 and '32. Most advantageously, a circuit point 34 formed between resistors 30 and 32 is connected to a light-responsive resistance element 36 selectively to vary the RC time constant of the network 22 in response to voltage variations at the input lines 12 and 14.

A secondary winding 18!: of transformer 18 is connected to the circuit portion indicated by reference numeral 16 which may be connected to any suitable rectifier and filter circuit when a regulated DC output is desired, or may be connected directly to a current utilization means in the case where a regulated alternating-current is desired. A second circuit portion is provided by a secondary winding 18c for applying an operating potential to a light-emitting element 38. Preferably,

' a variable resistance 40 is connected in circuit with the lightemitting element 38 provide manual selection of the desired light output thereof to set the voltage value at the output circuit portion 16 of the voltage regulator 10. Preferably the light-emitting element 38 and the light-responsive resistance element 36 are located in a common housing adjacent one another and is here designated by the dotted area 42 circumscribing these elements. A current path from the primary winding 18a to the resistance capacitance network 22 is provided by a series resistance 44 to apply a control signal producing voltage during each half-cycle of an applied alterhating-current voltage.

It will be noted that resistor 44 and capacitor 28 are connected in parallel with the bidirectional current control device 20, and the charge-across capacitor 28 as determined by the RC time constant of the circuit as provided by theresistance value of resistor 44 together with the parallel resistors 32 and 36. The charge on capacitor 28 is also applied to capacitor 26 determined by the time constant afforded by resistors 30 and 36. When the charge on capacitor 26 reaches the breakover voltage value of the reference voltage device 24 the device 24 substantially instantaneously conducts current into the gate electrode a of the bidirectional current control device 20 which, in turn, allows current flow to pass through the primary winding 18a. Since the current control device 20 is rendered conductive substantially instantaneously upon the breakover condition of the threshold voltage device 24 the voltage at gate 20a is substantially increased and the voltage drop across the threshold voltage device 24 is correspondingly decreased to render the same nonconductive, this nonconductive condition remaining for the remainder of the corresponding halfcycle of the applied alternating-current voltage. Upon reversal of current. of the applied alternating-current voltage the operation of the resistance capacitance network 22 is substantially the same but with opposite polarity current flowing therethrough to again control current flow through the primary winding 18a for the next half-cycle of opposite polarity.

' In accordance with this invention, the resistor 36 is responsive to the light intensity of the light-emitting element 38 which tends to vary the RC time constant of capacitors 26 and 28. Since the light intensity of the light-emitting element 38 corresponds to the output voltage of the secondary winding 18: any change of voltage of the applied alternating-current will be sensed substantially instantaneously by the lightemitting element 38. A decrease in light intensity will cause a corresponding increase in resistance of the light-responsive resistance element 36, and an increase in light intensity will cause a corresponding decrease in resistance of the lightresponsive resistance element 36. Therefore, the change in resistance value of the light-responsive resistance element 36 will cause a corresponding change in the phase angle at which the current control device 20 is rendered conductive to regulate the voltage at the circuit portion 16.

Referring now to FIG. 2 there is seen an alternate arrangement of the voltage regulator circuit of this invention as incorporated in a power supply suitable for use in color television sets. Here a pair of input circuit lines 51 and 52 are arranged for connection to any suitable source of alternating-current voltage and wherein there is provided a high-frequency filter choke 53 connected in transformer relation in each of the lines 51 and52 to buck out and substantially eliminate all high-frequency noise and signals which may be impressed on the applied voltage. The power from lines 51 and 52 is delivered to a primary winding 54a of a transformer 54 through an on-off switch 56. in accordance with this invention, a bidirectional current control device 57 is connected in series with the other end of the primary winding 54a and is rendered conductive at the appropriate phase angle by means of a light-responsive resistor. Any suitable overload protection device such as a fuse 58 may be connected in series with one of the lines 51 and 52.

The several secondary windings of transformer 54 may have any suitable turn ratio as is necessary for the proper operation of a television set, or the like. For example, a secondary winding 54b may be provided for producing suitable heater-filament voltage to the picture tube of a television set, and a secondary winding 54c may be provided for substantially increasing the voltage value of the applied alternating-current voltage to a value in the order of 350 to 400 volts which is used as 8+ and is applied to the various circuit components as represented by a load 60. Also, if desired, a top 54d may be provided on the secondary winding 54c to apply an alternating-current voltage to an automatic degaussing circuit within a color television set in the usual and well-known manner.

A bridge rectifier circuit 62 has its AC input terminals connected to the secondary winding 54c and its DC output terminals connected between a circuit line 64 which is connected to ground potential and a circuit line 66 which is connected to a filter network 68. Here the filter network 68 is illustrated as comprising a pair of series inductors 70 and 72, a resistor 74, and a pair of capacitors 76 and 78. However, it will be noted that the particular arrangement of the filter circuit components may be altered or changed as desired. I

A third secondary winding 54e has the output thereof connected to a light-emitting element 80 through a fixed resistor 82 and a variable resistance 84. The light-emitting element 80 is positioned adjacent a light-responsive resistance element 86, they preferably being located within a common housing inv dicated by reference numeral 88. The light-responsive resistor 86 functions in substantially the same manner as the lightresponsive resistor 36 of FIG. 1 to'control the phase angle at which the current control device 57 is rendered conductive to allow current to flow through the primary winding 54a of transformer 54. To this end, light-responsive variable resistance element 86 is connected to a circuit point 90 between a pair of resistors 92 and 94 which, in turn, are connected to one end of a pair of capacitors 96 and 98, respectively. The juncture of capacitor 96 and resistor 92 are connected to a bidirectional threshold-switching device which, in turn, is connected to the gate electrode 570 of the current control device 57. The charging current is applied to capacitor 98 through a series resistor 99 connected to the primary winding 54a of a transformer 54. The voltage-regulated portion of power supply 50 functions in substantially the same manner as that disclosed with regard to FIG. 1 and further explanation is deemed unnecessary.

in the arrangement shown in FIG. 2 the load 60 may draw current in the order of 1 amp. more or less, and the capacitance values of capacitors 76 and 78 together with the resistance value of resistor 74 are selected so as to supply current to the load 60 at a sufficient rate so that the integrated value of current pulses through the primary winding 54a results in a regulated DC voltage output.

Some of the advantages obtained by using the voltage regulator circuit of this invention are: the regulator circuit has internal feedback regulation rather than an external feedback by means of a control voltage or control current; the regulator circuit does not need an isolation transformer since the control element, i.e., the light bulb 38 or 80, is not connected to the primary of the transformer; the need of an oscillator circuit is eliminated thus eliminating 'the need of a separate power supply for such oscillator circuit; and the voltage level at which regulation will begin can be set at any desired level, here it being in the order of about 30 volts at the input lines 12 and 14 or $1 and 52.

Although a step-up transformer is shown in the illustrated embodiments it will be understood that a step-down transformer, or both, may be used. as well as a transformer having a one-to-one ratio. Also, there could be a number of taps on the secondary windings as well as on the primary winding to supply voltage to various circuit points, and all such taps would be regulated. Also it will be understood that the energizing voltage to the light bulb 38 or 80 could be obtained directly from the main secondary winding 1812 or 54c since the voltage applied to the bulb is adjusted by a variable resistance element.

By utilizing the voltage regulator circuit of this invention in electronic equipment which has electron tubes as its active elements, heater-filament voltage is accurately controlled within prescribed limits and the usable life of such electronic tubes can be greatly increased, in some cases by as much as 50 percent. This is particularly desirable for controlling the heater-filament voltage on television picture tubes which are relatively expensive to replace, especially a tri-gun color television picture tube.

Therefore, the voltage regulator of this invention provides efficient and inexpensive means for controlling the voltage value applied to any suitable load to a given predetermined voltage value regardless of voltage variations at the input line of the voltage regulator.

I claim:

1.. A voltage regulator circuit comprising in combination, a transformer having a primary winding for connection to a pair of input lines for receivingalternating-current voltage to be regulated, a first secondary winding for connection to output circuit lines for supplying a regulated load current to a load, and a second secondary winding for developing a voltage output which varies in response to voltage variations of the applied alternating-current voltage, a bidirectional current control device having load electrodes connected in series with said primary winding, and a control electrode for receiving control signals, a light-responsive resistance element connected in circuit with said control electrode to vary the phase angle at which said current control device is rendered conductive by the alternating-current voltage, a light-emitting element connected in circuit with said second secondary winding of said transformer to produce a light intensity output responsive to the voltage value developed in said second secondary winding, said light-emitting element positioned in light-transmitting relation to said light-responsive resistance element to vary its resistance value with changes in light intensity which varies the phase angle at which said current control device is rendered conductive and causes a corresponding variation in alternating-current voltage at said primary winding to vary the voltage output of said first secondary winding.

2. The voltage regulator circuit of a claim 1 wherein said bidirectional current control device is a bidirectional multilayer current control rectifier.

3. The voltage regulator circuit of claim 1 further including a manually adjustable resistance means connected in circuit with said second secondary winding and said light-emitting element manually to adjust a given light intensity from said light-emitting element to set the desired voltage output from the voltage regulator circuit.

4. The voltage regulator circuit of claim 1 including a first capacitor connected in circuit with the control electrode of said current control device, a resistor connected in series with said first capacitor and arranged for receiving current directly from said primary winding to apply a charge to said capacitor, corresponding substantially to the applied alternating-current voltage, said light-responsive resistance element connected across said first capacitor to vary the RC time constant thereof in response to the resistance value of said light responsive resistance element to control the phase angle of the firing if said control device, and coupling means connected between said first capacitor and the control electrode of said current control device for applying said control signal thereto.

5. The voltage regulator circuit of claim 4 wherein said coupling means include a threshold-switching device connected in series with the gate electrode of said current control device and the output of said first capacitor.

6. The voltage regulator circuit of claim 5 including a second capacitor, first and second resistance elements connected between respective ends of said first and second capacitors to form a common circuit point between said first and second resistance elements, said light-responsive resistance elements being connected to said common circuit point to control the rate of charge of said first and second capacitors in response to the amount of light impinged thereupon by said light-emitting element. 

1. A voltage regulator circuit comprising in combination, a transformer having a primary winding for connection to a pair of input lines for receiving alternating-current voltage to be regulated, a first secondary winding for connection to output circuit lines for supplying a regulated load current to a load, and a second secondary winding for developing a voltage output which varies in response to voltage variations of the applied alternating-current voltage, a bidirectional current control device having load electrodes connected in series with said primary winding, and a control electrode for receiving control signals, a light-responsive resistance element connected in circuit with said control electrode to vary the phase angle at which said current control device is rendered conductive by the alternating-current voltage, a light-emitting element connected in circuit with said second secondary winding of said transformer to produce a light intensity output responsive to the voltage value developed in said second secondary winding, said lightemitting element positioned in light-transmitting relation to said light-responsive resistance element to vary its resistance value with changes in light intensity which varies the phase angle at which said current control device is rendered conductive and causes a corresponding variation in alternating-current voltage at said primary winding to vary the voltage output of said first secondary winding.
 2. The voltage regulator circuit of claim 1 wherein said bidirectional current control device is a bidirectional multilayer current control rectifier.
 3. The voltage regulator circuit of claim 1 further including a manually adjustable resistance means connected in circuit with said second secondary winding and said light-emitting element manually to adjust a given light intensity from said light-emitting element to set the desired voltage output froM the voltage regulator circuit.
 4. The voltage regulator circuit of claim 1 including a first capacitor connected in circuit with the control electrode of said current control device, a resistor connected in series with said first capacitor and arranged for receiving current directly from said primary winding to apply a charge to said capacitor corresponding substantially to the applied alternating-current voltage, said light-responsive resistance element connected across said first capacitor to vary the RC time constant thereof in response to the resistance value of said light responsive resistance element to control the phase angle of the firing if said control device, and coupling means connected between said first capacitor and the control electrode of said current control device for applying said control signal thereto.
 5. The voltage regulator circuit of claim 4 wherein said coupling means include a threshold-switching device connected in series with the gate electrode of said current control device and the output of said first capacitor.
 6. The voltage regulator circuit of claim 5 including a second capacitor, first and second resistance elements connected between respective ends of said first and second capacitors to form a common circuit point between said first and second resistance elements, said light-responsive resistance elements being connected to said common circuit point to control the rate of charge of said first and second capacitors in response to the amount of light impinged thereupon by said light-emitting element. 